It is known that a measurement target object is divided in multiple divided systems and a transfer function of the measurement target object as a whole is estimated from transfer functions of the divided systems. The measurement target object as a whole is also referred to herein as a whole system.
When a measurement target object is, for example, a complicated apparatus, there are many resonance components or anti-resonance components in a frequency response characteristic associated with acceleration in response to input of a certain force. When there are many resonance components or anti-resonance components, a processing load (arithmetic operation load) for calculating a transfer function of a divided system by curve fitting or the like is excessively large, and a result, it becomes impossible to calculate the transfer function of the divided system in some cases. In a conventional transfer function synthesis method, when it is impossible to calculate the transfer function of the divided system, it is impossible to estimate the transfer function of the whole system. If the curve fitting is performed by using only a part of the resonance components or the anti-resonance components in order to calculate the transfer function of the divided system, information other than the used frequency components is missing. Thus, the estimation of the transfer function of the whole system by calculating the transfer function of the divided system has a low estimation precision by the missing information.